Steam generating and superheating unit with fixed jet blowers directed at superheater platens



June 14, 1960 R. M. HARDGROVE 2,940,430

STEAM GENERATING AND SUPERHEATING UNIT WITH FIXED JET BLOWERS DIRECTEDAT SUPERHEATER PLATENS Filed Nov. 16, 1955 3 Sheets-Sheet 1 INVENTOR.Ralph M. Hardgrove ATTORNEY June 14, 1960 R. M. HARDGROV E STEAMGENERATING AND SUPERHEATING UNIT WITH FIXED JET BLOWERS DIRECTED ATSUPERHEATER PLATENS Filed NOV. 15, 1955 3 Sheets-Sheet 2 INVENTOR. RalphM. Hardgrove ATTORN EY.

June 14, 1960 R. M. HARDGROVE 2,940,

STEAM GENERATING AND SUPERHEATING UNIT WITH FIXED JET BLOWERS DIRECTEDAT SUPERHEATER PLATENS Filed Nov. 16, 1955 a Sheets-Sheet 3 FIG.5

INVENTOR.

Ra h M. Hardgrove ATTORNEY 'iited States Patent STEAM GENERATING ANDSUPERHEATING UNIT WITH FIXED JET BLOWERS DIRECTED AT SUPERHEATER PLATENSRalph M. Hardgrove, North Canton, Ohio, assignor to The Bahcock & WilcoxCompany, New York, N.Y., a corporation of New Jersey Filed Nov. 16,1955, Ser. No. 547,193

3 Claims. (Cl. 122-392) This invention relates to fixed jet air blowersfor removing accumulations such as the stalactites of slag dependingfrom the ends of the spaced platens of a superheater disposed within theupper part of a furnace chamber, the furnace having associated therewithmeans for burning a slag forming fuel which, in the operation of theassociated steam generating and superheating unit, results in theaccumulations upon the ends of the platens nearest the fuel burningmeans in the form of stalactites,

which are most diflicult to remove.

In spite of numerous suggestions which may have been made with referenceto slag removal from such fluid heating tubular units disposed in thepath of high temperature furnace gases carrying slag particles insuspension, it has been one of the most difi'icnlt and vexing problemsin the art of high pressure steam generation and superheating tomaintain superheater platens in a sufl'iciently high gas temperaturezone to attain steam superheat temperatures of the order of 1100 degreesF., and keep them in operative condition, because of the slagaccumulations upon the portions of the superheater components nearestthe fuel burning means. The superheater platens have been spaced apartwidely enough to prevent the slag bridging between successive platens,but the slag accumulations still persist to such an extent that theyinterfere with effective heat transfer and efiicient operation of theunit, even when frequent lancing is practiced. V I v 1 a This inventionsolves this problem by providing fixed jet air blowers, each directedagainst the extreme lower part of a tubular superheater componentmost'subjeot to slag accumulation in the operation ofthe unit.

The invention will be set forth in concise manner in the appendedclaims, but for a more complete understanding of the invention, itsuses, and advantages, recourse should be had to the followingdescription which refers to the accompanying drawings in which apreferred embodiment of the invention is shown.

In the drawings:

Fig. 1 is a vertical section or sectional side elevation showing thearrangement of the fixed air jet air blowers with reference to thesuperheater platens;

Fig. 2 is a partial plan-or horizontal section upon the line 22 of Fig.l;

Fig. 3 is a detailed horizontal section of one of the fixed jet airblowers showing its association with adjacent tubes of the furnace wall,taken on the line 33 of Fig.4;

Fig. 4 is a fragmentary vertical section of the elements of Fig. 3;

Fig. 5 is a fragmentary plan or horizontal section taken upon the planeof the line 55 of Fig. l; and

Fig. 6 is a fragmentary horizontal section illustrating a few of thetubes of a superheater platen in association with a horizontal fluidconducting platen spacer tube constructed and arranged to maintain thesuperheater platens in their operative relationships.

Fig. 1 of the drawing illustrates a steam generating 2,940,430 PatentedJune 14, 1960 v unit having a cyclone furnace 10 burning particle formsolid fuel having slag forming characteristics, and operating attemperatures above the fusion temperature of the incombustible in thefuel. The illustrative cyclone furnace fired unit is of the type shownin the patent to Kerr et al. 2,594,312. Crushed coal, in particle form,is fed to the cyclone furnace 10 through the fuel burning means 12 andcombustion supporting air is simultaneously delivered to the furnacelllthrough the tangentially directed opening 14 to burn the fuel at thepertinent high temperature within the furnace. During operation of thefurnace molten slag flows from the lower part thereof through theopenings 16 while the combustion gases flow from the cyclone furnacethrough its throat 18 into the primary furnace chamber 20. The moltenslag continues to flow along the bottom of the primary furnace chamberand then through the slag exit opening 22 into the slag pit 24.

The high temperature combustion gases from the primary furnace chamber20 flow upwardly across the steam generating screen tubes 26,appropriately connected into the fluid circulation of the unit, suchconnections including lower connections to the submerged drum 28, andupper connections to the steam and water drum 30, as illustrated in Fig.1.

The high temperature furnace gases with particles of fused slagsuspended therein pass upwardly from the tubular screen 26 through thelower part 32 of the secondary furnace chamber where they contact thelower ends of spaced superheater platens 34 and 36, which are widelyspaced across the flow of gases and connected to receive steam from thesteam and water drum 30in a manner specifically shown in the pendingapplication Serial No. 336,525, now-Patent No. 2,834,324 filed in thename of G. J. Schoessow, on February 12, 1953,and belonging to the sameassignee. The disclosure of this application also involvesthe details ofthe means for holding the spaced superheater platens in their operativerelationships, such meansflinvolving the platen spac; ing tubesindicated at 40 and 42 in-Fig. 5. These tubes pass through the platensas .indicated'in Figs. 1 and '6 and have welded thereon projecting lugssuch as 44-47 (Fig. 6) arranged'on opposite sides of the tubes of asuperheater platen 35. Fig. 6 indicates four tubes 36A, 36B, 36 and36"of a platen 36 with the platen tube 36' having secu red thereto lugs 50and 51, which co-act with the associated lugs 44 and 45, on the platenspacing tube 42 in a manner similar to which the lugs 54 and 56 on thetube 36" co-act with the platen spacertube lugs 46 and 47. Thisarrangement of elements permits the platens to expand or contractrelative to the spacer tubes 40 and 42, While the superheater platensare still maintained in their operative spaced relationship.

The superheater platens are disposed in the gas flow in the upper partof the furnace chamber, the rear wall of which is common to that furnacechamber and a downflow convectiongas pass 60, in which other componentsof the convection heating apparatus of the unit are disposed. Suchcomponents are indicated at 6264, as convection superheater sectionsinvolving banks of horizontally extending and vertically spacedsuperheater tubes disposed transversely of the downfiow of gases withinthe gas pass 60.

The wall 76 separating the upper part of the secondary furnace chamber32 from the downflow gas pass 60 extends to the flue or exit of thedownflow gas pass from the gas exit 78 of the furnace chamber. At theposition of this exit the gases flow to the right from the top of thefurnace chamber 32, and to the top of the downflow gas pass 60.

*Fig. 1 indicates the steam generating tubes of thewall 76 as extendingfrom the submerged drum or header 28 Spaced and arranged in screenformation :across the gas exit ofthe furnace chamber 32. a r

At the level indicated by the numeral 70 in Fig. 1 the tubes of the wall76, or some ofz'them, are hentibut of their wall formingalignment'indicated at 96 in Fig.' 2. Such {bent ,out' portions areindicated-at 98jand 1101 in 2.,Atthe positions'in whichthe tubes arebent but of their wall forming alignment in this manner there are fixedjet air blowers lfl i, Each of these jets has 'aft ube such as thatindicatedat 106m Fig.3, witha' 'tapered end providin'gthe nozzle108,theexit end of which i's'welded to thewalltubes 100 and 99as'indicated'at 71 10 and '112. The upper and lower Walls1=114-and I116(Fig.4.) of each nozzle are welded :as indicated at 1 18 and .120 toflat intertube studs, such as 122'an'd 124 which,rin turn, are weldedtothe tubes. Thus, each jet is held in such a position that the streamof highvelocity t airdirected from .thenozzle is aimed at one of, theplatens 36, ,and atra position at the extreme lower end of the V platen,asfclearly indicated in Fig. 1. H

*Itis to heunderstood that there is onefo'f the fixed jet air blowerswith its nozzle arranged in the above describedmanner for each of theplatens 34 and 36.; Q'Ihe blowers 13 extend through the front wall 132of the unitjat the level 72 in the mannerindicated in Fig. 2, and dected against the extreme'lower end of the platens 34Ias indicatediuFig; 1. Thejnozzles of blowers130 are arranged with reference to thewall tubes 136 of the front wall of the steam. generating unit in amanner similartothat 1 above describedwith reference to the tubesofthewall.76; t a 7 m i The above described fixed jet air blowers,mayjlead fromheaders, such as 'thehea'ders 140 and 1142 fitom whichappropriate conduits lead through the valves 1144 and 1516 tolthetubular portions 106 or the'jets'.,

and other enclosure portions, including the rear wall 17 0,

. the' ro'of 172, the primary furnace chamber the inclined wall 176 'ofthe lower partfofjthe rfurrrace =chaniber32ythese enclosure 'portionsincluding heat'in W i a arranged ,to discharge alfluidjet in the planeof-a c orrespondingtube platen T and directediat the lower end thereofsulatingmaterial, as is well understood'infthis'i a It is alsowto'beunderstood that the walls of'the' cyclone a furnace ltlinvlove heatresisting refractory and eXteriorlyt arranged'heat insulating. materialin conjunction with w alls defining a vertically elongated housinghaving a furnace chamber in the lower part and a vertical upflow gaspassin the upper, part thereof, means for burning a slag-forming solid-fuelat temperatures above the slag fusion temperature in said furnacechamber, vertically 7 arranged fluid heating tubes lining said frontwall, a

plurality'ofgroupsofnested u -shap'e-d fluid heating tubes in saidupflow gas pass arranged to form a row of transversely spaced topsupported pendant radiantly heated tube platens arrangedin parallelvertical planes normal to said front wall and in position to have theirlooped lower end portions impacted by slag-laden higlitemperature gasesfrom {said' furnace chamber, a series of fluid jet nozzlesfixedlylpositioned in said front wall at transversely spaced positionstherein, and each of said fluid jet nozzles having its discharge endpositioned between and 1 terminating in heat transfepcontact with a pairof fluid heating tubes lining'said front wall and arranged to disghargea fluid jetrin the plane of a corresponding'tube platen andtdirected atthe lower end'thereof to clear said tube platen of slag depositing onthe lower end thereof. 2. A fluid heating unit comprising front, sideand rear walls defining a vertically elongated housing having a furnacechamber inrthe lower part thereof, means for vertically arranged fluidheating t tubes lining said front wall and baflie, a pluralityof groupsof nested U-shaped fluidjheating tubes. in sa'id upflow gas passarranged to form a row of transversely spacedetop-supported pendantradiantly heated tube platens arranged in parallel verticalplanesflnorma'l to said'front wall andsaidbafile and in position to havetheir looped lower end- .portionsimpacted by slag-laden high temperaturegases from said furnace chamber, a series of'fiuid jet nozzles fixedlypositioned inijsaid front wall at transverselyspacedipositions therein,arse'cond series ofoppositely arranged fluid jet nozzles; mounted: onsaid baflie-gat transversely spaced 7 -position s therein, and eachofsaid fluidjet' noz zles-in steam generating tubes generallysemi-circular, andlead ingifrom the lower header 180 to the upperheader, 182 which may be appropriately connected intothe fluidcirculation of the unit as above'indicatedin greater detail in theco-pendingapplication and the patent'ident'ified above,'and belonging tothe fsarne assignee.

' 1 Some of the pressure parts of the unit are disposed Whereastheinvention has been descrihedrefersaid first and second series having-itsdischarge ,endp'ositioned between and terminating adjacent-to a pair offluid heatingtubes in said frontwwall and bafile respectively andtocle'ar said tube platen ofslag depositing on'the lower end thereof. 7a 1 1 1 3. A fluid heating unit comprisingfront, side and rear vwallsdefining Y a vertically elongated housing having a a verticallyextending baffle extending between said side furnace chamber in thelower part thereof, means for burning a slag forming solid fuel attemperatures above the slag fusion temperaturein said'fur'nacef-chamber,

- 1 walls and intermediate said frontand rear walls and cooperatingtherewith to define a vertical upflow gas pass opening at its lower endto said furnace chamber and an adjoining serially connected verticaldownflow'gas pass, vertically arranged fluid heating tubes lining said'front wall and bafile, a plurality of groups oficlosely spaced nestedU-shaped fluid. heating tubes in said upflow gas pass arranged to formfront and rear rows of transversely spaced top-supported pendantradiantly heated tube platens arranged in parallel vertical planesnormal to said front wall andsaidbafiie and'infposition to have e'ncertoa preferredembodiment indicated in lthe-draw- 7 ings, it isto'herecognized' that the invention is not to he regarded as limited to allof the-details disclosedand described. is' rathe'r tobe considered asascope com- 1 mensurate with the scope of the sub-joined claims. I twhatisclaimed is: V

f "1.A'flnid heating unit 'comprisingfr'ontj'side and rear their loopedlower *end' portions impacted by slag-laden high temperature gases fromsaid'lfurna'ce chamber, means ior'holding the tube'platens in each rowdntransversely spaced relation, a seriesloffluid jet nozzles fixedlypositioned in said front wall-atrtran sversely-spaced positions therein,a second series ofoppositely arranged fluid jet nozzles mounted on saidbaflie at transversely spaced positions therein, and each of said fluidjet nozzles in said first and second series having its discharge endpositioned between and terminating adjacent to a pair of fluid heatingtubes in said front wall and bafiie respectively in heat transfercontact therewith and arranged to discharge a 5 fluid jet in the planeof a corresponding tube platen and directed at the lower end thereof toclear said tube platen of slag depositing on the lower end thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,608,866 Snow Nov. 30, 1926

